Update README.md

Author: Dev_Nergis

README.md

@@ -4,3 +4,8 @@ Ez-Test-Distributed-Mirror
 ```bash
 sudo docker run -it --rm ghcr.io/krfoss/etdm:latest
 ```
+
+- 미러주소 지정
+```bash
+sudo docker run -it --rm -e MIRROR_URL=kr.mirror.tefexia.net ghcr.io/krfoss/etdm:latest
+```